This invention relates to an automatic film feeder for feeding developed films into a photographic printing machine to an exposure position thereof.
To print photographic films, it is usually necessary to detect the image information for each frame of the film at a scanner unit and feed the film into the exposure station. In printing, the quantity of light is adjusted on the basis of detected image information.
There are two known methods of feeding developed films into the printing machine. One is to manually feed film strips one by one. The other is to automatically feed a plurality of films after winding them in a roll.
The former method has a problem in that films cannot be printed efficiently enough.
The latter method has the following drawbacks.
Positioning of a film is carried out by detecting the position of the blank portions between the adjacent image-carrying frames of a film when detecting image information for each frame. But not all the frames are distinguishable from the adjacent frames. If a film has a frame having a portion undistinguishable from the adjacent blank portions, no exact positioning of the film is possible. Thus, the film has to be manually pulled back and fed forward again for repositioning
When a film is fed backward in the feeder, it necessarily slackens. Thus, in order to feed the film backward, a space is necessary for the film to slacken in the feeder. But none of the conventional automatic film feeders has such space, so that it was impossible to feed films backward for repositioning of an undetectable frame.
An object of this invention is to provide a film feeder which makes it possible to feed a film backward for repositioning of any frame which is not detectable at the scanner unit.